[#585] Cleaning up JSON* classes

A number of JSON* classes were introduced in the repository (591b6d3d7ff44643dc637cd94e2fafac131697f7) and we also have multiple JSON processing libraries.  Cleanup eliminates some of the libraries.  Eventually we should use a single library for all JSON processing.
Yep. I imported it but just cross checked and the *remove unused imports* option is not selected for some reason. Will take a closer look at why.